1. Field of the Invention
The present invention relates generally to liquid dispensing devices. More particularly the invention concerns an improved precision reagent metering and delivery device having a rotating base and a fixed reagent container.
2. Discussion of the Prior Art
There exists in the prior art a wide variety of volumetric devices for dispensing liquids such as reagents. On one end of the spectrum is the simple manual type, such as the pipette, wherein a quantity of liquid is sucked up into a graduated tube and then discharged as a metered quantity. On the other end of the spectrum are various highly sophisticated mechanical and electromechanical devices adapted to reproducably dispense precise quantities of liquid from conventional or specicially designed reagent containers. The manual type devices often lack the necessary precision, while the mechanized devices frequently are unduly complex, extremely costly and, in many instances, tend to fail or malfunction in continuous use.
The apparatus disclosed in U.S. Pat. Nos. 3,834,241 issued to Garren et al and in 4,054,061 issued to Valt are exemplary of manual type pipette devices.
The apparatus disclosed in U.S. Pat. Nos. 3,931,915 issued to Downings et al and in 4,101,283 issued to Sundstrom are exemplary of mechanical and electromechanical dispensing devices. The latter mentioned Sundstrom device is specifically adapted for use in accurately pipetting specified digitally programmed volumes of sample and the delivery of likewise specified, digitally programmed, volumes of reagent. The thrust of the Sundstrom invention is directed toward the provision of a specially constructed plunger which is rotated within a non-threaded reagent container. Rotation of the plunger is controlled by a relatively sophisticated light-photo cell system which is operably interconnected with motor means through somewhat complex counting and connecting circuits. As a result of the particular configuration of the Sundstrom plunger, it cuts grooves in the inner wall of the reagent container as it rotates.
One of the most successful reagent metering and dispensing devices developed to date is described in the co-pending application Ser. No. 557,913 filed by the present inventor.
The device of the present invention is an improvement of the device described in Ser. No. 557,913 and is readily distinguishable from the prior art in that it solves the problems inherent in the precision delivery of large or small liquid aliquots by providing inexpensive and positive a simple, inexpensive and positive acting, but yet highly precise device for accurate reagent metering and delivery. As will be appreciated from the description which follows, because of its simplicity, the device of the present invention is easy to maintain and clean, is highly reliable in operation and can readily be operated by unskilled, non-professional personnel.